Apparatus, method, and program for creating all-around acoustic field

Abstract

In an apparatus for creating an all-around acoustic field, a producing section ( 4 ) is composed of a selecting section ( 41 ) for selecting one pair of right and left head transfer functions at an angle corresponding to an arriving direction of a reflected sound out of data of head transfer functions in whole directions stored in a storage section ( 5 ) on the basis of data of arriving directions of reflected sounds, an equalizing section ( 42 ) for equalizing a pair of right and left head transfer functions selected by the selecting section ( 41 ) by using frequency characteristic data of reflected sounds, a delaying section ( 43 ) for delaying the pair of right and left head transfer functions equalized by the equalizing section ( 42 ) by using delay time until a reflected sound arrives at a sound receiving point, and an adding section ( 44 ) for obtaining two channels of right and left impulse responses by accumulating the delayed pair of right and left head transfer responses.

1 . An apparatus for creating an all-around acoustic field, producing an acoustic field with respect to incoming audio-signals on the basis of analyzed data of an acoustic field at a sound receiving point designated in a space to be objected for reproducing the acoustic field, comprising: 
 storage means for storing data of head transfer functions in whole directions at respective positions of both ears of a human head;    producing means for producing two channels of right and left impulse responses by replacing a direct sound and each reflected sound at the sound receiving point with a pair of right and left head transfer functions by using the analyzed data of an acoustic field and the data of head transfer functions in whole directions; and    acoustic field processing means for processing to reproduce an acoustic field with respect to the incoming audio signals by using the two channels of right and left impulse responses produced by the producing means,    the producing means further characterized by comprising;    selecting means for selecting data of one pair of right and left head transfer functions of the direct sound at an angle corresponding to an arriving direction of the direct sound out of the data of head transfer functions in whole directions on the basis of data of arriving directions of direct sounds as the analyzed data of an acoustic field at the sound receiving point, and for selecting data of a pair of right and left head transfer functions with respect to the each reflected sound at an angle corresponding to an arriving direction of the each reflected sound out of the data of head transfer functions in whole directions on the basis of data of arriving directions of each reflected sound as the analyzed data of an acoustic field at the sound receiving point;    equalizing means for equalizing the pair of right and left head transfer functions selected by the selecting means with respect to the selected direct sound on the basis of data of frequency characteristics of a direct sound at the sound receiving point as the analyzed data of an acoustic field, and for equalizing the selected pair of right and left head transfer functions with respect to the selected each reflected sound on the basis of the data of frequency characteristics of a reflected sound at the sound receiving point as the analyzed data of an acoustic field;    delaying means for delaying a pair of right and left head transfer functions with respect to the equalized direct sound on the basis of data of arrival delay time of a direct sound at the sound receiving point as the analyzed data of an acoustic field, and for delaying a pair of right and left head transfer functions with respect to the equalized each reflected sound on the basis of data of arrival delay time of a reflected sound at the sound receiving point as the analyzed data of an acoustic field; and    adding means for obtaining the two channels of right and left impulse responses by adding the delayed data of the pair of right and left head transfer functions obtained with respect to the direct sound to the delayed data of the pair of head transfer functions obtained with respect to the each reflected sound equivalent to a number of sound rays of reflected sounds in each of the right and left channels respectively.    
     
     
         2 . The apparatus for creating an all-around acoustic field in accordance with  claim 1 , further comprising low pass filter means for fetching out only respective low frequency components of the two channels of right and left impulse responses produced by the producing means and for producing impulse responses of low frequency components by adding each of the fetched out respective low frequency components, 
 the apparatus further characterized in that the acoustic field processing means processes to reproduce an acoustic field with respect to the incoming audio signals by using the two channels of right and left impulse responses and the impulse responses of the low frequency components.    
     
     
         3 . A method for creating an all-around acoustic field, producing an acoustic field with respect to incoming audio signals on the basis of analyzed data of an acoustic field at a sound receiving point designated in a space to be objected for reproducing the acoustic field, comprising steps of: 
 storing data of head transfer functions in whole directions at respective positions of both ears of a human head;    producing two channels of right and left impulse responses by replacing a direct sound and each reflected sound at the sound receiving point with a pair of right and left head transfer functions by using the analyzed data of an acoustic field and the data of head transfer functions in whole directions; and    processing to reproduce an acoustic field with respect to the incoming audio signals by using the two channels of right and left impulse responses produced in the step of producing,    the step of producing the two channels of right and left impulse responses further characterized by comprising steps of:    selecting data of one pair of right and left head transfer functions of the direct sound at an angle corresponding to an arriving direction of the direct sound out of the data of head transfer functions in whole directions on the basis of data of arriving directions of direct sounds as the analyzed data of an acoustic field at the sound receiving point, and for selecting data of a pair of right and left head transfer functions with respect to the each reflected sound at an angle corresponding to an arriving direction of the each reflected sound out of the data of head transfer functions in whole directions on the basis of data of arriving directions of each reflected sound as the analyzed data of an acoustic field at the sound receiving point;    equalizing the pair of right and left head transfer functions selected in the step of selecting with respect to the selected direct sound on the basis of data of frequency characteristics of a direct sound at the sound receiving point as the analyzed data of an acoustic field, and for equalizing the selected pair of right and left head transfer functions with respect to the selected each reflected sound on the basis of the data of frequency characteristics of a reflected sound at the sound receiving point as the analyzed data of an acoustic field;    delaying a pair of right and left head transfer functions with respect to the equalized direct sound on the basis of data of arrival delay time of a direct sound at the sound receiving point as the analyzed data of an acoustic field, and for delaying a pair of right and left head transfer functions with respect to the equalized each reflected sound on the basis of data of arrival delay time of a reflected sound at the sound receiving point as the analyzed data of an acoustic field; and    adding to obtain the two channels of right and left impulse responses by adding the delayed data of the pair of right and left head transfer functions obtained with respect to the direct sound to the delayed data of the pair of head transfer functions obtained with respect to the each reflected sound equivalent to a number of sound rays of reflected sounds in each of the right and left channels respectively.    
     
     
         4 . The method for creating an all-around acoustic field in accordance with  claim 3 , further comprising a step of passing low frequencies for fetching out only respective low frequency components of the two channels of right and left impulse responses produced in the step of producing and for producing impulse responses of low frequency components by adding each of the fetched out respective low frequency components, 
 the method further characterized in that the step of processing processes to reproduce an acoustic field with respect to the incoming audio signals by using the two channels of right and left impulse responses and the impulse responses of the low frequency components.    
     
     
         5 . A program for creating an all-around acoustic field, making a computer function as an apparatus for creating an all-around acoustic field for producing an acoustic field with respect to incoming audio signals on the basis of analyzed data of an acoustic field at a sound receiving point designated in a space to be objected for reproducing the acoustic field, wherein the computer is realized by the program to comprise: 
 producing means for producing two channels of right and left impulse responses by replacing a direct sound and each reflected sound at the sound receiving point with a pair of right and left head transfer functions by using data of head transfer functions supplied from a memory storing the analyzed data of an acoustic field and data of head transfer functions in whole directions at respective positions of both ears of a human head; and    acoustic field processing means for processing to reproduce an acoustic field with respect to the incoming audio signals by using the two channels of right and left impulse responses produced by the producing means,    the producing means further characterized by comprising:    selecting means for selecting data of one pair of right and left head transfer functions of the direct sound at an angle corresponding to an arriving direction of the direct sound out of the data of head transfer functions in whole directions on the basis of data of arriving directions of direct sounds as the analyzed data of an acoustic field at the sound receiving point, and for selecting data of a pair of right and left head transfer functions with respect to the each reflected sound at an angle corresponding to an arriving direction of the each reflected sound out of the data of head transfer functions in whole directions on the basis of data of arriving directions of each reflected sound as the analyzed data of an acoustic field at the sound receiving point;    equalizing means for equalizing the pair of right and left head transfer functions selected by the selecting means with respect to the selected direct sound on the basis of data of frequency characteristics of a direct sound at the sound receiving point as the analyzed data of an acoustic field, and for equalizing the selected pair of right and left head transfer functions with respect to the selected each reflected sound on the basis of the data of frequency characteristics of a reflected sound at the sound receiving point as the analyzed data of an acoustic field;    delaying means for delaying a pair of right and left head transfer functions with respect to the equalized direct sound on the basis of data of arrival delay time of a direct sound at the sound receiving point as the analyzed data of an acoustic field, and for delaying a pair of right and left head transfer functions with respect to the equalized each reflected sound on the basis of data of arrival delay time of a reflected sound at the sound receiving point as the analyzed data of an acoustic field; and    adding means for obtaining the two channels of right and left impulse responses by adding the delayed data of the pair of right and left head transfer functions obtained with respect to the direct sound to the delayed data of the pair of head transfer functions obtained with respect to the each reflected sound equivalent to a number of sound rays of reflected sounds in each of the right and left channels respectively.    
     
     
         6 . The program for creating an all-around acoustic field in accordance with  claim 5 , further making the computer realize to comprise low pass filter means for fetching out only respective low frequency components of the two channels of right and left impulse responses produced by the producing means and for producing impulse responses of low frequency components by adding each of the fetched out respective low frequency components, 
 the program further characterized in that the acoustic field processing means processes to reproduce an acoustic field with respect to the incoming audio signals by using the two channels of right and left impulse responses and the impulse responses of the low frequency components.